During development and writing test-cases you can improve your knowledge and learn a lot about

- JAVA-basics and language-specific features
- architecture/design of your project
- usability of your code and libraries
- wrong assumptions about how your code works

This talk takes you to a journey about how you can improve the quality of your code by developing basic test-cases first and try out a scenario beforehand. While doing this you can discover some nice features and unexpected restrictions of the JAVA-language.
We will have a look at some code-samples, the according test-cases written in JUnit 5 and explore impacts and possible solutions. We will also have a look at the limits of testability and reachability of a high test-coverage.